This invention relates to a control handle structure of an excavation work vehicle, which connects a maneuvering valve for boom swiveling, a maneuvering valve for boom up-and-down rocking, a maneuvering valve for arm rocking and a maneuvering valve for bucket pivoting, interlockingly to two maneuvering levers adapted for free bi-directional rocking maneuvering, in a manner capable of separate individual maneuvering and capable of simultaneous maneuvering in respective pairs.
In order to maneuver, as easily and as efficiently as possible, a maneuvering valve for boom swiveling, a maneuvering valve for boom up-and-down rocking, a maneuvering valve for arm rocking and a maneuvering valve for bucket pivoting, of an excavation work vehicle, a control handle structure is used that uses two maneuvering levers adapted for free crosswise rocking maneuvering, which are capable of maneuvering separately the individual valves and capable of maneuvering simultaneously them in respective pairs.
As for the interlocking connection of the two maneuvering levers and the four maneuvering valves in conventional instances, a mode has been adopted, wherein one interlockingly connects respective pairs of the maneuvering valves each closely interrelated as to the maneuvering, thus in two sets, and one respectively connects them simply to the said two maneuvering levers, via four interlocking systems comprising push-pull rods.
However, as to the interlocking relationship between said two maneuvering levers and four maneuvering valves, namely as to which particular maneuvering valve and which particular maneuvering valve to interlockingly connect to which particular maneuvering lever, it is different according to the custom prevailing in the respective countries of the world and to the particular manufacturers.
As is again referred to in detail in the later-described embodiment of this invention, it is generally the case that for instance in England they connect the maneuvering valve for boom up-and-down rocking and the maneuvering valve for bucket pivoting, interlockingly to one maneuvering lever adapted for free bi-directional rocking, and connect the maneuvering valve for arm rocking and the maneuvering valve for boom swiveling, interlockingly to the other maneuvering lever adapted for free bi-directional rocking, while in the U.S.A. they connect the maneuvering valve for arm rocking and the maneuvering valve for bucket pivoting, interlockingly to one maneuvering lever, and connect the maneuvering valve for boom up-and-down rocking and the maneuvering valve for boom swiveling, interlockingly to the other maneuvering lever.
Besides, there are some manufacturers also in Japan who adopt such interlocking connection structure as to maneuver the maneuvering valve for boom swiveling by the maneuvering of one maneuvering lever in the machine body back-and-forth direction.
In order to satisfy such requirements of the respective countries, including Japan as well, various forms of the maneuvering structures must have separately been manufactured, and it has thus been quite uneconomical.
Furthermore work efficiency is reduced when an operator having experience with the system of a particular manufacturer is used to operate another system, due to the operator's fear of performing erroneous maneuvers.